We propose to continue purification of E. coli replication proteins responsible for the conversion of phi X174 viral DNA to its replicative form (RF), the multiplication of these RF and, finally, the synthesis of viral strands. These proteins include: dnaB, dnaC, dnaG, proteins i, n and u, rep, and cisA. We intend to study the structures and functions of these proteins and to separate and examine the multiple steps which make up each of the replicative stages in the phi X174 cycle. We also plan to search for ways in which we may examine factors which control and regulate these proteins and steps in the replicative pathways. BIBLIOGRAPHIC REFERENCES: Scott, J.F., Eisenberg, S., Bertsch, L.L. and Kornberg, A. A Mechanism of Duplex DNA Replication Revealed by Enzymatic Studies of Phage phi X174: Catalytic Strand Separation in Advance of Replication. Proc. Nat. Acad. Sci. USA 74, 193-197 (1977). McHenry, C. and Kornberg, A. DNA Polymerase III Holoenzyme of Escherichia coli: Purification and Resolution into Subunits. J. Biol. Chem., in press (1977).